Process for the recovery of phenols



Patented Feb. 22, 1944 UNITED, STATES PATENT OFFICE raooass mu mnncovaax or muons Henry G. Berger, Edwin H. Nygaard, and Henry 8. Angel,Woodbury, N. .I., assignors to Socony- Vacuum Oil Company, Incorporated,New York, N. 2., a corporation of New York No Drawing. ApplicationDecember 2, 1941,

Serial No. 421,328

:rived jirom caustic treatment oi. petroleum :aactions.

As is well known to those familiar with the art, crude petroleum oilsand distillate fractions obtained therefrom contain constituents otherthan compounds consisting only of carbon and hydrogen. Among these arecompounds containing sulphur, nitrogen, oxygen, etc. Generally suchoxygen compounds are represented by phenols, naphthenic acids, etc., andsuch sulphur compounds by mercaptans, thlophenes, disulfldes, etc.Varous methods are employed to extract these compounds irom thepetroleum fractions and methods have been proposed for recovery of thephenols so removed from the mixture in which they are extracted.Usually, phenols, naphthenic acids and mercaptans'are removed frompetroleum fractions containing these compounds by treatment with strongaqueous or alcoholic caustic solution. Such treatment converts phenolsto phenolates, naphthenic acids to naphthenates, and mercaptans tomercaptides. Then the caustic solution containing phenolates,naphthenates and mercaptides is separated from the oil; The causticsolution is then oxidized with H202, C12, 02, etc., to convertmercaptides to disulphides, which are insoluble in the caustic solutionand separate as an oil, which is withdrawn from the mixture. Thisprocedure is unsatisfactory, however, for part of the phenols aredestroyed by degradational oxidation; the undestroyed phenols remain insolution as' alkali metal phenolates in combination with the alkalimetal salts of the naphthenic acids; and some disulphides remainoccluded in the caustic solution. Thus, the processes proposed in theprior art do not provide for the complete removal of the sulphurcompounds, and do not provide for the production of substantially purephenols.

We have discovered a process which involves a novel sequence ofoperations for the recovery of phenols from the .caustic washliquorsobtained in the caustic treatment oi petroleum fractions. By thisprocess, phenols= substantially free of naphthenic acids and sulphur areobtained. The

process contemplated by this invention comprises the Iollowingoperations: admixing the caustic wash liquor from a caustic-treatedpetroleum fraction with an amount of sulphur suiiicient 3 Claims. (01.zen-saw) to convert the mercaptides to disuliides and with awater-immiscible organic solvent for disulfldes; agitating this mixtureand separating the caustic layer containing the phenolates and naphthesnates from the organic solvent layer containing the disulfldes,carbonating the caustic layer to convert the phenolates to phenols, andseparating the carbonated caustic solution containing the naphthenatesfrom the phenols. To eflect a more rapid and complete separation oi. thecarbonated caustic solution containing the naphthe'nates from thephenols, we contemplate the modification of adding a water-immiscibleorganic solvent for phenols to the carbonated caus- 1 tie layer,separating the carbonated caustic solution containing the naphthenatesfrom the sol- -vent layer containing the phenols and evaporating saidsolvent from the phenols. After these operations, the phenols aresubstantially tree of naphthenic acids and sulphur, and may be furtherpurified by steam distillation.

We also contemplate the recovery of phenols by means of the foregoingprocess from acidified caustic liquors of petroleum iractions containingphenols, naphthenic acids and mercaptans. To convert the acid solutioncontaining phenols, naphthenic acids, mercaptans and oil to a causticsolution corresponding to the original caustic solution in the aforesaidprocess, the following steps are taken: distilling with steam or vacuumthe acid solution containing "phenols, naphthenic acids, mercaptans andoil to as low a residue as possible, discarding the residue, extractingthe distillate with a water-immiscible organic solvent and extractingthe solvent with a-10% caustic solution, separating the phases bywithdrawing the caustic layer from the organic solvent layer containingneutral oil and organic residuum, discarding the organic solvent layer,

poses of our invention.

and treating the caustic layer according tov the liquors recovered fromthe caustic treatment or. I

The term "caustic liquor" used herein describes a liquor obtained'bytreatment of a pe troleum fraction with an alkali hydroxide, as forexample, NaOH, KOH, etc. For the purposes of economy and efliciency ofoperation, we have found NaOH most useful. And as aforesaid, we alsocontemplate the utilization of acidified caustic liquors as comingwithin the scope of this invention. When an acidified caustic liquor isused, it has been found that desired results are obtained when a slightexcess of alkali hydroxide is used over the amount required to combinewith the acidic components in the solvent layer.

Suitable solvents are those designated as water-immiscible organicsolvents. Such solvents as benzene, ether, chloroform, carbontetrachloride, etc., and low-boiling petroleum distillates, asforexample, petroleum ether are preferred.

To demonstrate the invention, the following typical example is given:

EXAMPLE An acidified spent caustic wash liquor containing a crudemixture of phenols, naphthenic acids and sulphur compounds, andrepresented by data given-in Tables 1 and 2, was treated as describedbelow:

306 grams'of the crude material were steam distilled, the temperature ofthe distilling liquid being about 130 C. The distillate was extractedwith petroleum ether and the aqueous layer ex-- tracted again with freshpetroleum ether to remove from it the bulk of the residual organicmaterial. The combined petroleum ether extracts were now agitated with350 cc. of sodium hydroxide. This amount of sodium hydroxide representsa slight excess over the amount required to combine with the acidiccomponents in the petroleum ether layer. The caustic and petroleum etherlayers were separated. The residue obtained by evaporating the solventfrom the petroleum ether layer amounted to seven grams and wasdiscarded; this represents neutral oil.

The sodium hydroxide layer was agitated vigorously with 600 cc. of apetroleum ether solution saturated with sulphur until a small portion ofthe petroleum ether layer indicates complete conversion of the sodiummercaptides to disulfides. This is evidenced by a negative doctor testby which SH-- and -S-M groups, wherein M is a metal, as. for example,Na, are shown to be absent from the solution. The sodium hydroxide andpetroleum ether layers are now separated. Removal of petroleum etherfrom this extract yields organic disulfides.

The sodium hydroxide layer was now carbonated with carbon dioxide. Thecarbonation causes a separation of the phenols from the aqueous layercontaining sodium naphthenates. The phenolic layer may be separated fromthe aqueous layer, or for a more complete separation the 5 mixture isextracted with a. water-immiscible organic solvent. For example, thiscarbonated mixture was extracted with 150 cc. of petroleum ether. Thepetroleum ether layer containing the phenols was separated and thepetroleum ether steam distillation.

The aqueous sodium carbonate layer was acidified with hydrochloric acid.This causes a separation of the free naphthenic acids which can be drawnon or can be further purified by distillation.

Results of this example are summarized in Table 3 given below:

TABLE 3 Summary of data on products obtained after processing originalmaterial Per cent Grams Per cent Per cent Product isolated of total phurg g fgi,

Neutral oil 5. 0 l. 6 23.0 7. 6 21. 5 7. 1 100. 5 33. 0 Residue 62. 020. 3

, Represented by Loss water content- 22. 0 7. 2 By manipulation..- 72.023. 5

1 Includes an excess of elementary sulphur used in the conversion ofsodium me'rcaptides to disulfides.

Thus, the eflicacy of our process is demonstrated by the sulphur contentof the purified phenols as compared with the over-all sulphur content ofthe original material. As shown in Table 1,

the sulphur content of the original material is 2.72%, and in Table 3,the sulphur content of the purified phenols is only 0.2%.-

It is to be understood that theforegoing speciflc example is forillustrative purposes only and that various modifications may be madetherein by those skilled in the art without departing from the scope ofthe appended claims.

We claim:

1. The process for the, recovery of phenols from aqueous caustic liquorscontaining phenolates, naphthenates and mercaptides derived from a crudecaustic-treated petroleum fraction from which neutral oils have beenremoved, comprising the following sequence of operations: admixing saidaqueous caustic liquor with a water-immiscible organic solvent fordisulfides and an amount of sulphur sumcient to convert said mercaptidesto disulfides; agitating this mixture and separatcrude caustic-treatedpetroleum fraction from which neutral oils have been removed,comprisevaporated, leaving the phenols as a residue. If 4 desired, thephenols may be further purified by ing the aqueous caustic layercontaining the ing the following sequence of operations: admixin; saidaqueous caustic liquor with a water-immiscible organic solvent fordisulfides and an amount 01! sulphur suflicient to convert saidmerorganic solvent for phenols; separating the carbonated aqueouscaustic solution containing the naphthenates from the. solvent layercontaining the phenols; evaporating said solvent from the phenols; andpurifying the phenols by steam distillation.

3. The process for the recovery of phenols from aqueous caustic liquorscontaining phenolates, naphthenates and mercaptides derived from acrude'caustic-treated cracked petroleum distil v 3 late from whichneutral oils have been removed, comprising the following sequence ofoperations: admixing said aqueous caustic liquor with petroleum ether todissolve disulfides and an amount of sulphur suflicient to convert saidmercaptides to disulfldes, agitating this mixture and separating theaqueous caustic layer containing the phenolates and naphthenates fromthe petrole um ether layer containing the disulfides; carbonating saidaqueouscaustic layer to convert the phenolates to phenols and aiding theseparation of the two phases by adding petroleum ether to dissolvephenols; separating the carbonated aqueous solution containing thenaphthenates from the petroleum ether layer containing the phenols;evaporating petroleum ether from the phenols; and purifying the phenolsby steam distillation.

' HENRY G. BERGER.

EDWIN M. NYGAARD. HENRY S. ANGEL.

CERTIFICATE OF CORRECTION. Patent No. 2,5u2, s6. February 22, 191m.

HENRY a. BERGER, ET AL.

It is hereby certified thaterror appears in the printed specification ofthe above numbered patent requiring correction as follows: Page 5, firstcolumn, line 8-9, c1a;1.m'2, for "carbonating the caustic .ayer toconvert [381d aqueous read -carbonating said aqueous caustic layer toconvert t e"; and that the said Letters Patent should be read with thiscorrection therein that the same may conform to the record of the casein the Patent Office.

si ned and sealed this 9th day of May, A. D. 19%.

Leslie Frazer (seal) Acting Commissioner of Pater zts,

